Which wavelength of light is most effective for photoactivation of cones?

The wavelength of light that is most effective for photoactivation of cones is 495 nm. This wavelength is within the blue-green spectrum of visible light and corresponds to the peak sensitivity of the short-wavelength sensitive (S) cones, which are responsible for detecting blue and violet hues.

Cone photoreceptors are sensitive to specific ranges of wavelengths, and each type of cone (S, M, and L) has a characteristic absorption spectrum that defines its peak sensitivity. The M cones, which are sensitive to medium wavelengths (green), show peak sensitivity around 530 nm, while L cones, sensitive to longer wavelengths (red), peak around 560 nm.

Understanding the sensitivity of these cones allows insights into color vision and the role light plays in activating these photoreceptors. The choice of 495 nm as the correct answer reflects an understanding of the biological mechanisms of vision and the specific roles of different types of cones in color perception. The other wavelengths mentioned might engage the cones differently or may be less effective due to the intrinsic sensitivity of the cones.